Methods are sought which improve the state of the art of chemical synthesis of polypeptides. Three types of new methods are sought: protective groups that can be removed under selective and mild conditions; protective groups that allow affinity separation of products; and amide forming reagents that employ the amine capture strategy. In this strategy, the amine component of a peptide coupling reaction is engaged in covalent bond formation, prior to the amide forming step. Amide bond formation then occurs intramolecularly by an acyl transfer from an ester function to the amine group of the captive amine component. The coupled peptide is then released in a final step. The advantages of this strategy are likely to be evident, only if the chemical reaction that results in amine capture involves functional groups that exhibit large and selective mutual affinity. Variants of this strategy in which acyl transfer occurs via medium-sized rings and in which capture occurs at an amino acid side chain are being explored. Reagents that meet the conditions of model experiments are being explored through synthesis of important peptide hormones, such as somatostatin.